This invention relates to a bending device, which can both control a feeding speed of a longitudinal material and apply an axial compressive force to the material.
As disclosed in the Unexamined Japanese Patent Publication No. 2-274321, when feeding a longitudinal material through a bending mechanism at a high speed, a known conventional device engages a first clutch to transmit rotation of a motor to a drive shaft by way of a first transmission mechanism and then moves a feeding table toward the bending mechanism by means of the drive shaft to feed the material.
During bending, which requires a compressive force along the axis of the material, the device selects and engages a second clutch. This second clutch transmit rotational of the motor to 1) the drive shaft by way of a second transmission mechanism at a moderating ratio larger than that of the first transmission mechanism, and 2) moves the feeding table by driving the drive shaft with a large driving force to generate an axial compressive force in the material.
However, such conventional devices require a plurality of clutches and a plurality of these devices requires an unnecessarily large amount of space.
An object of the present invention is to provide a bending device which is small in size but able to feed a material at a high speed. Another object of the present invention is to provide a bending device which applies an axial compressive force to the material.
To attain this and other objects, the present invention provides a bending device for moving a feeding table. The bending device is equipped with a chuck mechanism for gripping a longitudinal material, and a bending mechanism to bend the material therein.
The bending device comprises a hydraulic actuator for moving the feeding table, and a hydraulic circuit. The hydraulic circuit can be selectively switched between a speed control channel and a pressure control channel. The speed control channel for supplies operating oil from a hydraulic source to the hydraulic actuator by controlling the speed of the operating oil. The pressure control channel supplying operating oil from the hydraulic source to the hydraulic actuator by controlling the pressure of the operating oil.
A hydraulic pump which can vary its discharge rate may be used for the hydraulic source and a hydraulic motor may be used for the hydraulic actuator. A servo valve may be provided in the speed control channel. A pressure reducing valve may be provided in the pressure control channel.